Display device with light diffusive glass panel

ABSTRACT

A display device ( 10 ) having a display element ( 20 ), such as a light-emitting device or a light-reflecting device, such as a MEMS device, and a glass touch panel ( 30 ) covering the display element, the outer surface ( 50 ) of the panel being textured. The panel is thin, having a thickness of 1.1 mm or less between the inner ( 40 ) and outer ( 50 ) surfaces.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119 ofU.S. Provisional Application No. 61/418,023 filed on Nov. 30, 2010, thecontent of which is relied upon and incorporated herein by reference inits entirety.

FIELD

The present specification generally relates to display devices and, morespecifically, to electronic display devices having a glass panel.

SUMMARY

Disclosed herein is a display device comprised of a display element anda glass panel covering the display element. The display element can beeither a light-emitting device, such as a backlit device, or alight-reflecting device (such as a device with no backlighting, e.g.reflects ambient light, such as a MEMS display, or an electrophoreticdisplay (EPD)), and the display element is configured to display animage toward the glass panel. The glass panel is light diffusive, andpreferably is scratch resistant and thermally, chemically, andmechanically robust. In some embodiments, the glass panel is a glasstouch panel. The glass panel can be either low alkali, or alkali-free,and in some embodiments contains no alkali.

In some embodiments, the glass panel provides greater than 90% totaltransmittance and haze greater than 75%.

In some embodiments, the display element is a micro electromechanicalsystem (MEMS) device, an electrophoretic display (EPD, a liquid crystaldisplay (LCD) device, a digital light processing (DLP) device, or aliquid crystal on silicon (LCOS) device.

In a first aspect, a display device is disclosed herein comprised of alight-reflecting device and a glass touch panel covering thelight-reflecting device. In one set of embodiments, the light-reflectingdevice is a MEMS device, such that the display device disclosed hereinis comprised of a MEMS device and a glass touch panel covering the MEMSdevice. In another set of embodiments, the light-reflecting device is anEPD device, such that the display device disclosed herein is comprisedof an EPD device and a glass touch panel covering the EPD device.

In one set of embodiments, a display device is disclosed hereincomprising a MEMS device and a glass touch panel covering the MEMSdevice. The glass touch panel contains no alkali, has a CTE of 50×10⁻⁷/°C. or less, and a scatter ratio (diffuse transmittance divided by totaltransmittance) of 0.5 or more, the panel having opposing inner and outersurfaces, the inner surface facing the MEMS device in an inwarddirection, and the outer surface facing away from the MEMS device in anoutward direction, the outer surface being textured, the inner surfacebeing non-textured, the panel having a thickness of 1.1 mm or lessbetween the inner and outer surfaces, the panel having a total forwardtransmission of 90% or more in the outward direction.

In another set of embodiments, a display device is disclosed hereincomprising a MEMS device and a glass touch panel covering the MEMSdevice. The glass touch panel contains no alkali, has a CTE of 50×10⁻⁷/°C. or less, and a scatter ratio (diffuse transmittance divided by totaltransmittance) of 0.75 or more, the panel having opposing inner andouter surfaces, the inner surface facing the MEMS device in an inwarddirection, and the outer surface facing away from the MEMS device in anoutward direction, the outer surface being textured, the inner surfacebeing non-textured, the panel having a thickness of 1.1 mm or lessbetween the inner and outer surfaces, the panel having a total forwardtransmission of 90% or more in the outward direction.

In a second aspect, a display device is disclosed herein comprised of adisplay element and a cover glass covering the display element. In oneset of embodiments, the display element is a light-reflective device,such that the display device disclosed herein is comprised of alight-reflective device having a substrate surface facing outward and acover glass bonded to and covering the light-reflective device. Thecover glass can be an ion-exchanged strengthened glass, such as CorningIncorporated's Gorilla® glass.

Additional features and advantages of the invention will be set forth inthe detailed description which follows, and in part will be readilyapparent to those skilled in the art from that description or recognizedby practicing the embodiments described herein, including the detaileddescription which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description describe various embodiments and areintended to provide an overview or framework for understanding thenature and character of the claimed subject matter. The accompanyingdrawings are included to provide a further understanding of the variousembodiments, and are incorporated into and constitute a part of thisspecification. The drawings illustrate the various embodiments describedherein, and together with the description serve to explain theprinciples and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic view of a display device asdisclosed herein comprised of a light-emitting device and a glass panelcovering the light-emitting device.

FIG. 2 shows total transmittance after media blasting and etching for aglass panel formed from Corning Incorporated's EAGLE XG® glass.

FIG. 3 shows four different haze textures (ultra-high, high, medium andlow haze textures, from top to bottom) to select for a glass panelformed from Corning Incorporated's EAGLE XG® glass.

FIG. 4 shows the haze measurements (i.e. scatter ratio, defined as theratio of diffuse transmittance divided by total transmittance) for ahigh haze light diffusive glass panel formed from Corning Incorporated'sEAGLE XG® glass.

FIG. 5 shows angular scattering (i.e. corrected bidirectionaltransmittance distribution function (ccBTDF) in units of (sr)⁻¹) for amedium haze light diffusive glass panel at 400, 600, 800 and 1000 nm,formed from Corning Incorporated's EAGLE XG® glass.

FIG. 6 shows angular scattering (i.e. corrected bidirectionaltransmittance distribution function (ccBTDF) in units of (sr)⁻¹) for ahigh haze light diffusive glass panel at 400, 600, 800 and 1000 nm,formed from Corning Incorporated's EAGLE XG® glass.

FIG. 7 shows total reflectance measurements for a high haze lightdiffusive glass panel formed from Corning Incorporated's EAGLE XG®glass.

FIG. 8 schematically illustrates the fabrication of a display devicedisclosed herein comprising a MEMS device.

FIG. 9 schematically illustrates a display device disclosed hereincomprised of a MEMS device that includes a MEMS array and a glass panel.

FIG. 10 schematically illustrates a display device disclosed hereincomprised of an EPD device and a glass panel, where the glass panelserves as the common electrode substrate of the EPD device.

FIG. 11 schematically illustrates a display device disclosed hereincomprised of a cover glass and a display element, such as alight-reflective device, for example an EPD device.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of displayapparatus comprising a glass panel and methods of making the same,examples of which are illustrated in the accompanying drawings.

Referring to FIG. 1, a display device 10 is disclosed herein comprisedof a display element 20 and a glass panel 30 covering the displayelement 20. The display element 20 is configured to display an imagetoward the glass panel 30. The panel 30 has an inner surface 40 andouter surface 50, i.e. opposing inner and outer surfaces 40, 50. Theinner surface 40 faces the display element 20 in an inward direction,and the outer surface 50 faces away from the light-emitting device 20 inan outward direction. Thus, the display element 20 is configured todisplay an image toward the inner surface 40 of the glass panel 30. Theouter surface 50 is textured so as to be light diffusive. Thus, theglass panel 30 is light diffusive. The inner surface 40 is not textured,i.e. non-textured. The panel 30 has a thickness “T”.

In some embodiments, the thickness of the glass panel is about 1.1 mm orless, in some embodiments about 0.7 mm or less, and in some embodimentsabout 0.5 mm or less.

In some embodiments, the inner surface 40 is disposed on or near thedisplay element 20. In some embodiments, the inner surface 40 is bondedto the display element 20. In some embodiments, the inner surface 40directly contacts the display element 20.

Preferably, the glass panel 30 provides high light transmission and lowbackscatter for the light impinging upon the inner surface 40 of theglass panel 30. In some embodiments, the glass panel 30 has a totalforward transmission of 90% or more in the outward direction.

In some embodiments, the inner surface 40 of the glass panel 30 is flat,such as in embodiments where the display element 20 is a MEMS device; insome of these embodiments the glass panel 30 is selected from a fusiondrawn glass, a polished glass, or a polished fusion drawn glass; in someembodiments the inner surface 40 of the glass panel 30 is a polishedinner surface.

In some embodiments, the glass panel 30 is not coated. In someembodiments, the outer surface 50 of the glass panel 30 is not coated.In some embodiments, no anti-reflective coating is present on the outersurface 50 of the glass panel 30.

In some embodiments, the correlation length of the outer surface 50 ofthe glass panel 30 is greater than 500 nm and lower than 2 microns. Insome embodiments, the correlation length of the outer surface of theglass panel is greater than 750 nm and lower than 1.5 microns.

In some embodiments, the RMS roughness of the outer surface 50 of theglass panel 30 is greater than 250 nm and smaller than 1.5 microns. Insome embodiments, the RMS roughness of the outer surface of the glasspanel is greater than 500 nm and smaller than 1.25 microns.

In some embodiments, the outer surface of the glass panel exhibits acosine corrected bidirectional transmittance distribution function(ccBTDF) of greater than 0.07 (sr)⁻¹ between −30 and +30 degrees about anormal axis to the outer surface of the glass panel.

In some embodiments, the outer surface of the glass panel exhibits accBTDF of greater than 0.10 (sr)⁻¹ between −20 and +20 degrees about anormal axis to the outer surface of the glass panel.

In some embodiments, the glass panel has a scatter ratio of 0.5 or morefor all wavelengths between 300 and 1200 nm; in some embodiments, theglass panel has a scatter ratio of 0.75 or more for all wavelengthsbetween 300 and 1200 nm; in some embodiments, the glass panel has ascatter ratio of 0.80 or more for all wavelengths between 300 and 1200nm; in some embodiments, the glass panel has a scatter ratio of 0.85 ormore for all wavelengths between 300 and 1200 nm; in some embodiments,the glass panel has a scatter ratio of 0.90 or more for all wavelengthsbetween 300 and 1200 nm; and in some embodiments, the glass panel has ascatter ratio of 0.95 or more for all wavelengths between 300 and 1200nm.

The glass panel is preferably scratch resistant, and thermally,chemically, and mechanically robust. In some embodiments, the glasspanel is a glass touch panel. The glass panel is either low alkali, oralkali-free, and in some embodiments contains no alkali. By “low-alkali”is meant less than 2 wt % alkali. By “alkali-free” is meant essentiallyno alkali, where trace amounts might be present in the glass.

In some embodiments, the CTE of the glass panel matches a CTE of atleast a portion of the display element. In some embodiments, the CTE ofthe glass panel is within ±10% of a CTE of at least a portion of thedisplay element. In some embodiments, the glass panel has a CTE of lessthan 60×10⁻⁷/° C., and in some embodiments, a CTE of 50.0×10⁻⁷/° C. orless. In some embodiments, the glass panel has a CTE of between30.0×10⁻⁷/° C. and 50.0×10⁻⁷/° C.

The outer surface of the glass panel can be textured, such as bylapping, sandblasting or hydro-blasting, chemical etching andcombinations thereof, to provide appropriate total transmittance andhaze. The texture obtained will provide a selected range ofcharacteristic sizes and shapes in order to provide desired opticalproperties. In some embodiments, the texture comprises smoothed craters,with a characteristic diameter size in the micrometer range, in someembodiments 1 to 5 μm, such as obtained by a two-step method: a firststep of lapping or sandblasting that causes micro-cracks in the glasssurface and a second step of acid etching, which preferentially startson the edges of micro-cracks and rounds the edges to lead to a smootherpattern. The first step can comprise media lapping or blasting the glasssurface with a stream of fine abrasive particles, which is mixed inslurry with deionized (DI) water. In the case of lapping, such slurrydrips between glass and a lapping plate, while in the case ofsandblasting, slurry is propelled with compressed air. Water is combinedwith the abrasive to allow the use of finer abrasive particles than withair only, which overall produces fewer fractures on the surface as thewater acts as a damping medium on the impacting particles. The secondstep (acid etching) partially modifies the texture obtained after thefirst step and restores the glass surface strength after media lappingor blasting, which causes micro-cracks in the glass surface. The resultis a highly light diffusive surface with still high total transmittance,which allows improvement of light usage by decreasing the amount ofreflected rays.

In one embodiment, the glass panel is comprised of CorningIncorporated's EAGLE XG® glass. In another embodiment, the glass panelis comprised of Corning Incorporated's Gorilla® glass.

FIGS. 2-7 relate to various glass panels formed from CorningIncorporated's EAGLE XG® glass and processed by a two-step method asoutlined above, wherein: an abrasive solution was utilized which usedalumina particles with a fine mesh (#600, corresponding to 5 to 20 μmparticle size, with a median size at 10 μm), the alumina being used forits hardness, and the fine particle distribution being used to createsmall micro-cracks in the glass surface, wherein the load of thesolution was comprised between 20 and 80% by weight of alumina in water;for blasting conditions, the treatment time influenced the surfacefraction where abrasive impacts are created; samples were etched afterthe sandblasting or lapping step to partially modify the textureobtained after the first step and to restore the glass surface strength,as media blasting causes micro cracks in the glass surface, wherein a1:1:20 solution of HF:HCl:H2O was utilized for 5-15 minutes of etchingwas used; and all samples were rinsed and cleaned after etching step.

FIG. 2 shows total transmittance after media blasting and etching forthe light diffusive glass panel.

FIG. 3 shows four different haze textures (ultra-high, high, medium andlow haze textures, from top to bottom) to select for a glass panel.

FIG. 4 shows the haze measurements (i.e. scatter ratio, defined as theratio of diffuse transmittance divided by total transmittance) for ahigh haze light diffusive glass panel.

FIG. 5 shows angular scattering (i.e. corrected bidirectionaltransmittance distribution function (ccBTDF) in units of (sr)⁻¹) for amedium haze light diffusive glass panel at 400, 600, 800 and 1000 nm.

FIG. 6 shows angular scattering (i.e. corrected bidirectionaltransmittance distribution function (ccBTDF) in units of (sr)⁻¹) for ahigh haze light diffusive glass panel at 400, 600, 800 and 1000 nm.

FIG. 7 shows total reflectance measurements for a high haze lightdiffusive glass panel.

In one set of embodiments, a display device is disclosed hereincomprising a MEMS device and a glass touch panel covering the MEMSdevice. The glass touch panel is comprised of Corning Incorporated'sEAGLE XG® glass and has a CTE of 50×10-71° C. or less, and a scatterratio (diffuse transmittance divided by total transmittance) of 0.5 ormore, the panel having opposing inner and outer surfaces, the innersurface facing the MEMS device in an inward direction, and the outersurface facing away from the MEMS device in an outward direction, theouter surface being textured by the two-step process, the inner surfacebeing non-textured, the panel having a thickness of 1.1 mm or lessbetween the inner and outer surfaces, the panel having a total forwardtransmission of 90% or more in the outward direction. The inner surfaceis flat and smooth.

In another set of embodiments, a display device is disclosed hereincomprising a MEMS device and a glass touch panel covering the MEMSdevice. The glass touch panel is comprised of Corning Incorporated'sEAGLE XG® glass and has a CTE of 50×10-7/° C. or less, and a scatterratio (diffuse transmittance divided by total transmittance) of 0.5 ormore, the panel having opposing inner and outer surfaces, the innersurface facing the MEMS device in an inward direction, and the outersurface facing away from the MEMS device in an outward direction, theouter surface being textured by the two-step process, the inner surfacebeing non-textured, the panel having a thickness of about 0.3 mm betweenthe inner and outer surfaces, the panel having a total forwardtransmission of 90% or more in the outward direction. The inner surfaceis smooth, and the MEMS device comprises a MEMS array disposed on thesmooth inner surface. Thus, the textured outer surface would face theviewer with the viewer looking through the glass panel (or substrate) tothe array. Ambient light, and/or a front light outside the displaydevice, would reflect off the array back towards the viewer.

FIG. 8 schematically illustrates the fabrication of a display devicedisclosed herein comprising a MEMS device. A MEMS array is deposited onthe smooth inner surface 40 of a glass panel 30, the inner surface 40being opposite the textured outer surface 50. FIG. 9 schematicallyillustrates the display device 10 comprised of the completed MEMS device(including MEMS array) 20 and the glass panel 30.

In another set of embodiments, a display device is disclosed hereincomprising an EPD device and a glass touch panel covering the EPDdevice. The glass touch panel is comprised of Corning Incorporated'sEAGLE XG® glass and has a CTE of 50×10-7/° C. or less, and a scatterratio (diffuse transmittance divided by total transmittance) of 0.5 ormore, the panel having opposing inner and outer surfaces, the innersurface facing the EPD device in an inward direction, and the outersurface facing away from the EPD device in an outward direction, theouter surface being textured by the two-step process, the inner surfacebeing non-textured, the panel having a thickness of less than about 1.1mm between the inner and outer surfaces, the panel having a totalforward transmission of 90% or more in the outward direction. In someembodiments, the EPD device comprises a TFT array disposed on a lowersubstrate, the TFT array facing a common electrode disposed on an uppersubstrate; the non-textured (smooth) inner surface of the glass panel isdirectly bonded to upper substrate, such that the textured outer surfacewould face the viewer with the viewer looking through the glass panel tothe array; ambient light, and/or a front light outside the displaydevice, would reflect off the array back towards the viewer; the glasspanel thus acts as a cover glass. In other embodiments, the EPD devicecomprises a TFT array disposed on a lower substrate, the TFT arrayfacing a common electrode disposed on the non-textured (smooth) innersurface of the glass panel (the glass panel then serving as the uppersubstrate), such that the textured outer surface would face the viewerwith the viewer looking through the glass panel to the array; ambientlight, and/or a front light outside the display device, would reflectoff the array back towards the viewer; the glass panel thus acts as theupper substrate of the EPD device; such display devices preferably haveno front polarizer.

In another set of embodiments, a display device is disclosed hereincomprising an EPD device and a glass touch panel covering the EPDdevice. Referring to FIGS. 10 and 11, the EPD device is comprised of aTFT substrate 90, a TFT array 80 disposed on the TFT substrate, a commonelectrode substrate, a common electrode 60 disposed on the commonelectrode substrate, and ink capsules 70 disposed between the commonelectrode 60 and the TFT array 80. FIG. 10 schematically illustrates adisplay device disclosed herein comprised of an EPD device and a glasspanel 30, where the glass panel 30 serves as the common electrodesubstrate of the EPD device. In some embodiments, the glass panel 30 isCorning Incorporated's EagleXG® glass. FIG. 11 schematically illustratesa display device disclosed herein comprised of a display element such asa light-reflective device, for example an EPD device, and a cover glasspanel 30, wherein the outer surface 50 is textured. The cover glasspanel 30 can be Corning Incorporated's Gorilla® glass, and the commonelectrode substrate 55 can be Corning Incorporated's EagleXG® glass. Thecover glass panel 30 can be bonded to the common electrode substrate 55.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the embodiments describedherein without departing from the spirit and scope of the claimedsubject matter. Thus it is intended that the specification cover themodifications and variations of the various embodiments described hereinprovided such modification and variations come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A display device comprising: a display element;and a glass touch panel covering the display element, the glass touchpanel having no alkali or an alkali content of less than 2 wt %, a CTEof 50×10⁻⁷/° C. or less, and a scatter ratio (diffuse transmittancedivided by total transmittance) of 0.5 or more, the panel havingopposing inner and outer surfaces, the inner surface facing the displayelement in an inward direction, and the outer surface facing away fromthe display element in an outward direction, the outer surface beingtextured, the inner surface being non-textured, the panel having athickness of 1.1 mm or less between the inner and outer surfaces, thepanel having a total forward transmission of 90% or more in the outwarddirection.
 2. The display device of claim 1 wherein the CTE of the glasstouch panel is within ±10% of a CTE of at least a portion of the displayelement.
 3. The display device of claim 1 wherein the CTE of the glasstouch panel matches a CTE of at least a portion of the display element.4. The display device of claim 1 wherein the glass panel has a scatterratio of 0.5 or more for all wavelengths between 300 and 1200 nm.
 5. Thedisplay device of claim 1 wherein the glass panel has a scatter ratio of0.75 or more for all wavelengths between 300 and 1200 nm.
 6. The displaydevice of claim 1 wherein the glass panel has a scatter ratio of 0.90 ormore for all wavelengths between 300 and 1200 nm.
 7. The display deviceof claim 1 wherein the correlation length of the outer surface of theglass panel is greater than 500 nm and lower than 2 microns.
 8. Thedisplay device of claim 1 wherein the correlation length of the outersurface of the glass panel is greater than 750 nm and lower than 1.5microns.
 9. The display device of claim 1 wherein the RMS roughness ofthe outer surface of the glass panel is greater than 250 nm and smallerthan 1.5 microns.
 10. The display device of claim 1 wherein the RMSroughness of the outer surface of the glass panel is greater than 500 nmand smaller than 1.25 microns.
 11. The display device of claim 1 whereinthe inner surface is flat.
 12. The display device of claim 1 wherein theglass panel is fusion drawn glass.
 13. The display device of claim 1wherein the inner surface of the glass panel is a polished surface. 14.The display device of claim 1 wherein the outer surface of the glasspanel is not coated.
 15. The display device of claim 1 wherein the innersurface is disposed on or near the display element.
 16. The displaydevice of claim 1 wherein the inner surface is bonded to the displayelement.
 17. The display device of claim 1 wherein the inner surfacedirectly contacts the display element.
 18. The display device of claim 1wherein the outer surface of the glass panel exhibits a ccBTDF ofgreater than 0.07 (sr)⁻¹ between −30 and +30 degrees about a normal axisto the outer surface of the glass panel.
 19. The display device of claim1 wherein the outer surface of the glass panel exhibits a ccBTDF ofgreater than 0.10 (sr)⁻¹ between −20 and +20 degrees about a normal axisto the outer surface of the glass panel.
 20. The display device of claim1 wherein the display element is a micro electro mechanical system(MEMS) device, an electrophoretic display (EPD) device, a liquid crystaldisplay (LCD) device, a digital light processing (DLP) device, or aliquid crystal on silicon (LCOS) device.
 21. The display device of claim1 wherein the glass panel is a glass touch panel.
 22. A display devicecomprising: a MEMS device; and a glass touch panel covering the MEMSdevice, the glass touch panel having no alkali or an alkali content ofless than 2 wt %, a CTE of 50×10⁻⁷/° C. or less, and a scatter ratio(diffuse transmittance divided by total transmittance) of 0.5 or more,the panel having opposing inner and outer surfaces, the inner surfacefacing the MEMS device in an inward direction, and the outer surfacefacing away from the MEMS device in an outward direction, the outersurface being textured, the inner surface being non-textured, the panelhaving a thickness of 1.1 mm or less between the inner and outersurfaces, the panel having a total forward transmission of 90% or morein the outward direction.
 23. The display device of claim 22 wherein thepanel having a thickness of 0.5 mm or less between the inner and outersurfaces.